First of all, Illustrator needs almost 1-2 to start since the latest update. Before it was, like Photoshop, just a matter of some seconds.
When started, everything feels sluggish, changing the font for a text field is not possible anymore and I don't know how many more problems. The whole UI makes a somewhat broken impression, the cursor in textfields doesn't show and a whole lot more and is very unresponsive, takes seconds to react.

This is with a high-end setup with 64GB of RAM (of which 32GB are free when showing this behaviour, so it's not RAM shortage causing this, at least)